Rotary cutter heads



Dec. 15, 1959 s. F. SMITH- ETAL 2,917,091

ROTARY CUTTER HEADS Filed Feb. 24, 1958 INVENTORS 57/1 M5 Y fiffomlclr 5mm BY HUBER r Lesa; 60%;? Jada, W X fi m k ATTORNEYS produces an improved grip on the cutter or cutters. particular it is an object to provide an improved construc- ROTARY CUTTER HEADS Stanley Smith, New Malden, and Hubert L. Gower, Litton, England Application February 24, 1958, Serial No. 717,149

Claims priority, application Great Britain June 11, 1957 8 Claims. (Cl. 144-230) This invention relates to rotary cutter heads particularly for woodworking machines, and of the kind (hereinafter called the kind referred to) having a body formed with a parallel walled groove or grooves each for receiving an outwardly projecting cutter, the general plane of the 'groove being parallel with, but offset from, the axis of tion which prevents the withdrawal of the cutter or cutters from the head in a direction away from the edge of the head. A still further object of the invention is to provide a self-aligning clamping arrangement for the cutter or cutters.

According to the present invention there is provided a rotary cutter head of the kind referred to in which the clamping means is provided with self-aligning means so as to apply an even clamping force to the associated cutter.

In the preferred embodiment of the invention each of the recesses is formed in a wall of the groove which is nearer the axis of the body of the cutter head, the. recesses each having inner and outer walls which are mutually parallel for receiving the screw device which is urged axially towards the associated cutter by a nut which 7 is held against axial movement.

In. one construction the self-aligning means may comprise a pivotal connection between the clamping block and the screw device which allows universal movement ofthe clamping block relative to thetscrew device.

One form of pivotal connection comprises a transverse pin loosely connecting an axial extension of the clamping block within an axial aperture formed in the end of the screw device.

In a second construction the self-aligning means may take the form of a spherical member loosely mounted between the screw device and the clamping block so as to allow universal movement of the clamping block relative to the screw device.

According to a further feature of the invention a backing plate may be mounted in each of the grooves for engaging the surface of the cutter remote from the clamping block. In order to prevent movement of the cutter in a direction along the cutter groove the mating surfaces of the cutter and backing plate are both corrugated or grooved in a direction transverse to the direction of the cutter groove. In a modified arrangement the cutter surface may be corrugated or grooved also in a direction parallel to the direction of the cutter groove in order to allow the cutter to be provided with cutting surfaces on all its four edges.

States Patent 2,917,091 Patented Dec. 15, 1959 'In order that the invention may be clearly understood a preferred embodiment will now be described by way of example with reference to the accompanying drawings, in which:

Figure 1 is a side elevation of a cutter head provided with two cutters;

Figure 2 is a plan view of Figure 1;

Figure 3 is a perspective view showing the formation of the mating surfaces of the cutter and its backing plate;

Figure 4 is a sectional view on the line 4-4 of Figure 1 showing the mounting arrangement for the backing plate;

Figure 5 is a modified surface construction for the surface of the cutter which engages the backing plate; and

Figure 6 is a sectional view of a modified clamping device for the cutter.

Referring now to Figures 1 to 4 of the drawings there is shown a cutter head which comprises a flat cylindrical steel body 10 formed at its centre with an axial bore 11 to enable it to be attached to the usual spindle of a woodworking machine. The body 10 of the cutter head may be fitted to receive one or more cutters and in the embodiment shown two cutters are fitted one at each side of the axial bore 11. The cutters are shown at 12 and 13 and each is made of flat, hardened steel formed at its outer edge with the usual cutting edge 14-. The mounting and clamping means for each of the cutters l2 and 13 is identical and consequently only one will be described, the same reference numerals being used for the corresponding parts of each.

The cutter l2 fits into a deep, narrow groove 15 formed in the body It), the groove extending parallel with the axis of the body 10 with its plane disposed substantially chordwise. The cutter 12 is held in position in the :groove 15 by a clamping device which comprises a block 16 located in a recess 1'7 formed in the wall of the groove 15 which is nearer the axis of the body It). The block 16 is formed with an axial extension 18 which extends within an axial aperture 19 in a screw device indicated generally by the reference 20.

The screw device 26 comprises a block 21 which is slidably mounted within a parallel-sided notch or groove 22 cut into the body 10 to intersect the recess 17 extending from the cutter groove 15. The block 21 is loosely coupled to the axial extension 18 of the clamping block 16 by means of a pin 23 and the extension 18 is formed with a curved or domed surface 24 adapted to seat within a similarly shaped end of the block 21, so as to allow a universal movement of the clamping block 16 relative tothe block 21 of the screw device.

The screw device 24) is formed with an axial threaded extension 25 which is engaged by a nut 26 disposed within a parallel-sided notch or groove 26a cut intothe body 10 to intersect the groove 22. The axial extension 25 is supported in a bearing collar 2'7 fitted in the end of thegroove 22, the collar 27 also acting to restrain the nut 26 againstlongitudinal movement. It will be appreciated that -rotation of the nut 26 will move the screw device '20 longitudinally along the groove 22 to apply a compressive force on the clamping block 15 tothereby hold the eutter12in the groove 15. The upper surface of the screw device 21 is formed with a longitudinal groove or flat surface 23 which is engaged by an Allen screw 29 so as to prevent rotational movement of the screw device.

The face 30 of the cutter 12 remote from the clamping block 16 is formed with a plurality of transverse corrugations or grooves, for example, about & deep. The construction of the face 30 is shown more clearly in Figure 3 of the drawings and when the cutter is mounted in position in the groove 15, the corrugations or grooves 31 extend transversely to the direction of the groove 15.

The surface 30 of the cutter 12 is adapted to engage a backing plate 32 which also is formed with a face 33 provided with similarly shaped corrugations or grooves 34.

The backing plate 32 is held in position in the groove 15 by mounting means which is shown more clearly in Figure 4 of the drawings. The backing plate 32 is formed with an axial extension 35 which is apertured to receive a pin 36. The pin 36 is a loose fit in the aperture as will be seen in Figure 4 so as to allow the backing plate a small angular adjustment relative to the sides of the body for example, to allow for uneven wear along the cutter edge 14. The pin 36 is double-headed and the upper head 37 is externally threaded for engaging a threaded bore extending parallel to the groove and communicating therewith. The head 37 is an Allen screw which is adjustable from outside the body 10 as will be seen more clearly in Figure 2.

The width of the groove 15 and the clamping block 16 are such that the cutter 12 cannot be withdrawn along the direction of the groove 15 due to the mating grooves and corrugations 31 and 34 on the cutter 12 and the backing plate 32. Once the compressive force has been released by the nut 26 the cutter 12 can only be removed by a movement to one or other side of the cutter head. This arrangement provides for greater safety in the mounting of the cutter 12 as it avoids any possibility of the withdrawal or ejection of the cutter from the body 10 in a direction away from the edge of the head.

The provision of the connection between the clamping block 16 and the screw device 20 provides a selfaligning arrangement which ensures that an even clamping force is always applied by the block 16 to the cutter 12. The arrangement provides for an even and accurate clamping device to be applied without the necessity of manually adjusting any of the parts.

Referring now to Figure 5 there is shown a modified arrangement of the cutter 12 in which the surface is formed with corrugations or grooves in a direction also which is parallel with the groove 15. The provision of the additional grooves still only allows the cutter to be inserted from the side of the body 10 in view of the corrugations on the backing plate 32 but it allows the the cutter to be inserted to present any one of its four edges each of which may be formed with a cutting edge.

In Figure 6 there is shown a modified connection between the screw device 20 and the clamping block 16. In this arrangement the clamping block 16 is formed with an axial extension 33 which is shaped to form a seat for a steel ball 39. The ball 39 is similarly received within the seat in the block 21 of the screw device and the arrangement thus provides a loose coupling which allows the clamping block 16 to move universally relatively to the screw device 21 so as to apply an even and accurate clamping force to the cutter 12.

It is, of course, within the scope of the invention to provide a cutter blade having smooth surfaces and forthe self-aligning clamping block to hold such a cutter against the opposite wall of the cutter recess. Preferably, however, the backing plate would be retained in order to avoid undue movement of the clamping block and to this vend a backing plate may be used provided also with a smooth surface.

We claim:

1. A rotary cutter head comprising a body formed with one or more parallel walled grooves each for receiving an outwardly projecting cutter, the general plane of each of the grooves being parallel with, but offset from, the axis of the body, a recess formed in a wall in each of the grooves, a clamping device located in each of the said recesses, each of said clamping devices including a screw device and a clamping block, said screw device being operable to produce a compressive force which is imparted to the clamping block in line with the screw axis for holding the associated cutter in position in the groove, wherein each clamping device includes also a self-aligning means between said block and the screw device so as to ensure even clamping force over the surface of the cutter.

2. A rotary cutter head as claimed in claim 1, wherein each of the recesses is formed in a wall of the groove which is nearer the axis of the body of the cutter head, the recesses each having inner and outer walls which are mutually parallel for receiving the screw device which is urged axially towards the associated cutter by a nut which is held against axial movement.

3. A rotary cutter head as claimed in claim 1, wherein the self-aligning means comprises a pivotal connection between the clamping block and the screw device which allows universal movement of the clamping block relative to the screw device.

4. A rotary cutter head as claimed in claim 3, wherein the pivotal connection comprises a transverse pin loosely connecting an axial extension of the clamping block within an axial aperture formed in the end of the screw device.

5. A rotary cutter head as claimed in claim 4, wherein the contacting surfaces between the clamping block and the screw device are curved or dome-shaped in construction.

6. A rotary cutter head as claimed in claim 1, wherein ,a spherical member is loosely mounted between the screw device and the clamping block so as to allow universal movement of the clamping block relative to the screw device.

7. A rotary cutter head as claimed in claim 1, in which a backing plate is mounted in each of the grooves for engaging the surface of the cutter remote from the clamping block.

8. A rotary cutter head as claimed in claim 7, wherein the contacting surfaces of the cutter and backing plate are both corrugated, grooved or serrated in a direction transverse to the direction of the cutter groove so as to prevent movement of the cutter in a direction along the cutter groove.

References Cited in the file of this patent UNITED STATES PATENTS 1,011,107 Blood Dec. 5, 1911 1,190,197 Shimer July 4, 1916 1,269,378 Bunch June 11, 1918 1,549,036 Westgard Aug. 11, 1925 2,144,986 Miller Jan. 24, 1939 2,814,320 Dukes et al Nov. 26, 1957 FOREIGN PATENTS 556,993 Great Britain Oct. 29, 1943 675,367 France Nov. 7, 1929 

